This invention is directed to an apparatus for contacting an electronic componet with raised contact structures. This invention is particularly well suited for probing wafers with resilient contact structures.
It is well understood in the art of manufacturing semiconductor devices to test devices while still unsingulated from the wafer for some level of functionality. Conventionally this is done using a probe card and a prober. A representative probe card is illustrated in FIG. 1. The probe card is mounted in a prober, which in turn detects with high precision the position and orientation of the probe card, and the position and orientation of a wafer to be tested, then brings the two into precise alignment. The probe card is connected in turn to a tester, providing a connection between the tester and one or more devices on the wafer. The tester can energize the device under test (DUT) and evaluate the performance of the device. This process is repeated as needed to test substantially each device on the wafer. Devices which pass the test criteria are processed further.
One particularly useful probe card makes use of resilient spring elements for contacting the wafer. Such a probe card is illustrated in FIG. 1. This probe card is described in detail in U.S. Pat. No. 5,974,662, entitled xe2x80x9cMethod of Planarizing Tips of Probe Elements of a Probe Card Assembly,xe2x80x9d and the corresponding PCT Application published May 23, 1996 as WO 96/15458.
Semiconductor devices are manufactured on a semiconductor wafer but must be singulated and connected to external devices in order to function. For many years, the standard method of connecting a semiconductor has involved fabricating a semiconductor device with pads, typically of aluminum. These pads are connected to larger structures, typically a lead frame, typically using wirebonding. The lead frame can be mounted in a suitable package, typically of ceramic or plastic. The spacing of connections on the package is designed to mate with a circuit board or other mating device such as a socket. Various innovations in packaging over the years allow for relatively close spacing and ever-higher pin counts in packaging.
A significant change from this packaging paradigm is seen in BGA packaging. Here, the contact points are globules of a reflowable material. A solder material is commonly used, so that a package can be positioned at a contact area then heated to reflow the solder, providing a secure electrical connection. This same general strategy is used at the chip level, forming small bumps over contact areas. A commonly used process makes C4 balls (controlled collapse chip connection).
Conventional probe cards are designed to contact traditional bond pads, typically aluminum. The novel probe card of FIG. 1 is useful for this purpose. Probing C4 balls is more complex for a variety of reasons, but the probe card of FIG. 1 is particularly well suited for this purpose as well.
A new form of packaging has become available which allows formation of small resilient contact structures directly on a semiconductor wafer. This is the subject of several patents, including U.S. Pat. No. 5,829,128, issued Nov. 3, 1998. An illustrative embodiment is shown here in FIG. 2 as wafer 208 with springs 224 connected to terminals 226.
A large scale contactor has been disclosed for contacting some or all of a semiconductor wafer which is built with resilient contact elements. Fixturing and burn-in processes are described in copending, commonly assigned U.S. patent application Ser. No. 08/784,862, filed Jan. 15, 1997, now U.S. Pat. No. 6,064,213, which is incorporated herein in full by reference. The corresponding PCT application was published as WO 97/43656 on Nov. 20, 1997.
The present invention provides a probe card useful for probing a semiconductor wafer with raised contact elements. In particular, the present invention is useful for contacting resilient contact elements, such as springs.
A probe card is designed to have terminals to mate with the contact elements on the wafer. In a preferred embodiment, the terminals are posts. In a preferred embodiment the terminals include a contact material suitable for repeated contacts.
In one particularly preferred embodiment, a space transformer is prepared with contact posts on one side and terminals on the opposing side. An interposer with spring contacts connects a contact on the opposing side of the space transformer to a corresponding terminal on a probe card, which terminal is in turn connected to a terminal which is connectable to a test device such as a conventional tester.
It is an object of this invention to provide a probe card for probing a semiconductor device with raised contact elements.
xe2x80x9cIt is another object of this invention to probe card an electronic component with raised contact elements. Such an electronic component can include a packaged semiconductor such as a BGA package.xe2x80x9d
This and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings.